But why’s there so much turbulence amongst LD supporters?

This is the updated version of a chart that is featured often here – how declared LD supporters respond to YouGov’s question of whether they would prefer a Brown-led Labour government or a Cameron-led Tory one? This is asked every month of all voters but the chart just focuses on the Lib Dems.

Those surveyed are not given any other option and the results are probably a good pointer to potential tactical voting. They are also a good indicator of who is winning the battle for the middle ground.

These proportions will also be useful when trying to work out the impact of, say, the AV voting system. A piece by Rod Crosby will be published here next week.

What is extraordinary is the high level of turbulence. From a dominating position in February last year Brown’s Labour found itself behind amongst Lib Dem supporters nine months later. Now, as the chart shows, the position is almost back to the February 2006 level.

Quite why Lib Dems should change so rapidly is hard to say. You would have thought that the proportions of Labour and Tory waverers would have stayed fairly constant.

Given that Lib Dem supporters are main hunting ground for both main parties the picture looks good for Labour. But will it continue? Could the proportions return to what they were before Chritsmas?

A lot will depend on how long the current honeymoon goes on.

Mike Smithson